Good form - Steve Skinner reports on safer and more efficient falsework and formwork

Safer and more efficient falsework and formwork systems are helping contractors to meet ever tighter construction deadlines. Steve Skinner reports.

Safe working conditions are a basic social responsibility according to Doka's Stefan Pruckmayr, and especially so during the forming of a building's carcass.

"The preconditions for safety with formwork are established in the planning phase," he told CE. "We undertake detailed planning with contractors to provide the most efficient formwork solution for their projects, and also in order to eliminate potential hazards.

"The easier a formwork solution is to use and the more intuitive the routines become, the safer the site becomes and that ultimately pays off in higher productivity too," said Mr Pruckmayr.

Almost universally adopted now, perimeter protection systems play a major role in site safety. The newest system for the European market is Efco's Power Shield.

The Power Shield can protect up to five floors and is mounted close to the deck edge, reducing the space through which debris might fall. The all-steel design reduces the fire risk, while synthetic mesh, corrugated light gauge steel or polycarbonate panels allow light and air through to the working area.

Cathy Howell, advertising manager at Efco told CE, "The Power Shield is constructed in a modular format and is self-climbing so that it can climb with the formwork and doesn't require crane time."

Ischebeck Titan's full height safety screen offers workers natural lighting through the use of a mesh facing, which the company says also forms an effective barrier against wind. "The entire screen can be lifted by crane or hoist, and once positioned the screens are ready for immediate use," said a spokesperson.

At the BBC's new MediaCity UK development in Manchester, contractor Bovis Lend Lease awarded the in-situ concrete work to Heyrod Construction, which adopted Ischebeck Titan's full-height safety screens for Blocks A and B of the development.

"We needed to meet a Bovis stipulation for full height safety screens on the 25 and 21 storey blocks respectively," said Alan Hedgecock, project manager at Heyrod. "With Block A, the screen extended around the full 95 m perimeter to give all round protection across various levels."

Ischebeck Titan designed a bespoke screening system for the project using narrow screen panels to step around the curved profile of the building and shaped internal boards to offer protection on the inside.

"Five man teams were able to complete upwards of 500 m² of in-situ concrete decking in seven day cycles on Block A and 860 m² in eight day cycles on Block B, pouring one deck while back-propping two lower decks, all protected by the screens from deck to soffit," said Mr Hedgecock.

Heyrod's Vic Grady said, "The screens instilled such a high degree of confidence in the workforce that they made a positive contribution towards productivity."

Doka offers a complete range of safety systems from its XS ladder with integral cage, through the Xsafe platform system, to its range topping Xclimb 60 protection shield that can fully enclose four levels and can either self climb or be crane lifted.

"No matter how safe a design might be, the formwork material alone will not suffice to reduce the risk of accidents in the carcass phase," said Mr Pruckmayr. "The use of correct on-site working practices is equally important and that is why we are committed to hosting safety seminars to demonstrate potential risk areas," he said.

Table form

Hünnebeck believes it has cut labour costs by -25%, reduced crane time by -50% and cut transport and logistical costs by up to -70% through the introduction of its Topmax steel-framed table form.

Topmax features a 120 mm thick, hot-dip galvanised steel frame that encloses an easy to clean plastic form lining. "The thin profile of the 10 and 13 m² table forms enables excellent space-saving stacking," said a Hünnebeck spokesman. "And the smooth form lining is protected from damage by a permanently attached stacking protection system that remains in-situ throughout construction."

The Topmax formwork also has a folding head with a self-securing pin and engagement mechanism for quick assembly and the capacity to lift the leg through 180⁰.

"A key benefit of Topmax is that two table forms connected together with a centering clamp can be lifted as a single unit, which translates to moving 26 m² of shuttering plus the attached legs and fall protection rails in a single crane lift," said the spokesman.

Topmax also addresses the matter of adjustment formwork either through connecting to Hünnebeck's Rasto or Takko systems with a centering clamp for large adjustment areas, or through the use of timber for smaller gaps.

Doka has upgraded its composite timber-plastic Xlife sheet to extend the intervals between changing sheets. Mr Pruckmayr told CE, "The new Xlife sheet is long-lived, it can be nailed without difficulty and it's easier to clean and recondition. What is more, the surface structure ensures the very best concrete results even after many repeat uses."

For quadratic and rectangular columns, Doka has developed a folding mechanism for its KS Xlife formwork that means the four panels always stay connected as a single unit. The system can be adapted to column cross-sections of between 200 mm and 600 mm in 50 mm increments, by relocating bolts.

"The folding mechanism and shifting-wheels for crane-free horizontal transport make for rapid forming, and once in position KS Xlife unfolds in a few simple steps ready for forming," said Mr Pruckmayr.

To ensure a smooth, unspoiled concrete surface, the Xlife form-facing is screwed on from the rear, while for tight, clean corners frontal triangular ledges are clipped onto the edges of the sheets, thus eliminating the need for nailing.

KS Xlife also features Doka's XS ladder system with integral ladder cages to provide safe access to the pouring platform.

Meva's managing director, Gerhard Dingler told CE that the best investment decision the company's ever made was the switch to all-plastic facings. "We're quicker with logistics, we don't have many repairs and the high cost of re-facing is history for us. For sure, we've won clients because of our facings," he said.

Because of its confidence in its facings Meva has introduced what it calls "RentalPlus", an initiative the company anticipates will signal the end of disputes over damage to formwork.

Mr Dingler said, "The RentalPlus system is based on the addition of 0,045% of the rental rate as a premium, which then acts like an insurance against damage.

"This ‘insurance' means damaged or not, we accept our formwork systems back off rent and avoid any need for protracted discussions regarding damage and liability. This enables us to refurbish facings more quickly and get them back out on rent, enabling our customers to work."

Meva believes it is unique in this approach, which is only possible through its use of all-plastic facings. "These facings enable us to operate more efficient logistics, and because we only ever need to repair rather than re-face, our formwork is ‘in service' most of the time."

Meva's RentalPlus initiative is backed-up by a cross-border approach that means Meva's never heavily stocked in one country and short in another. "We invested strongly in inventory and rental yards up to the end of 2008 and despite the slowdown in the construction industry we're finding that rental is strong," said Mr Dingler.

Finish

While safety remains an on-going issue, the new technical director at Meva, Elias Maier told CE, "I believe issues in 2010 will be linked to releasing agents and architectural concrete, or finish."

Doka's Mr Pruckmayr shares the view when he says that it's important to get the very best concrete results and to limit the need for finishing work on concrete.

To add gravitas to the argument for improved finishing, John Crellin of HKR architects said, "One of the main architectural concerns is the quality of the surface finish because concrete is often deliberately exposed and therefore a smooth finish is paramount to the success of the design."

HKR designed the Hive project in Manchester city centre, an UK£ 11,5 million (€ 12.7 million), 10220 m² office building scheduled for completion in January.

The concrete frame contract was won by SGG Construction, which used SGB's Topec slab panel modular formwork to complete the work on time. "The simplicity and speed of the Topec system helped us achieve our goal of fast erection and dismantling, while also reducing the amount of space required for storage and assembly," said an SGG spokesman.

"SGB's Topec formwork met all the key criteria, including the overriding need to safeguard the health and safety of the workforce. Furthermore, it proved to be compatible with traditional formwork, which reduced the cost outlay," he said.

Pressure

The underlying drivers for the formwork sector will continue to be based on safety, but speed will play an increasingly important role.

"Contractors are demanding more and time pressures are therefore much greater," said Mr Dingler. "This is a situation that's here to stay and I believe because the technology is already at an advanced stage, contracts in the future will be won based on client service."